Date: 13 Dec 1995 00:00:01 EST

  The tpsc (SCSI tape) driver is a dynamically loadable kernel module,
  so it (like all such modules) is automatically unloaded five minutes
  after last use. This means that if you wait five minutes between
  writes to a no-rewind tape device, the driver will unload and the
  kernel will forget that it's not supposed to rewind on the next write.
  If you're running mediad (and haven't told it to ignore the tape
  device in question) it will query the device often enough to prevent
  the driver from unloading; this will prevent unexpected rewinds, but
  only as long as mediad continures to run.

  The problem will be fixed in IRIX 6.2; there is no patch. (Earlier
  editions of this FAQ said that patch 176 and its successors fixed the
  problem; that was an error.)  You can prevent the tpsc driver from
  unloading at all by adding an "N" to the field which contains "oscdR"
  in /var/sysgen/master.d/tpsc and rebuilding your kernel.  See also the
  mload(4) manpage.